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([2a01:4b00:bf28:2e00:ff96:2dac:a39:3e10]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a35ca4d1fasm9185328f8f.1.2025.05.23.09.10.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 23 May 2025 09:10:11 -0700 (PDT) Message-ID: <1d6a8908-01dd-4285-989c-0d7a6b4dbfd5@gmail.com> Date: Fri, 23 May 2025 17:10:10 +0100 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [bug report] bpf: Implement dynptr copy kfuncs To: Dan Carpenter , Mykyta Yatsenko Cc: bpf@vger.kernel.org References: Content-Language: en-US From: Mykyta Yatsenko In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/23/25 16:58, Dan Carpenter wrote: > Hello Mykyta Yatsenko, > > Commit a498ee7576de ("bpf: Implement dynptr copy kfuncs") from May > 12, 2025 (linux-next), leads to the following Smatch static checker > warning: > > kernel/trace/bpf_trace.c:3557 copy_user_data_sleepable() > warn: maybe return -EFAULT instead of the bytes remaining? > > kernel/trace/bpf_trace.c > 3551 static __always_inline int copy_user_data_sleepable(void *dst, const void *unsafe_src, > 3552 u32 size, struct task_struct *tsk) > 3553 { > 3554 int ret; > 3555 > 3556 if (!tsk) /* Read from the current task */ > --> 3557 return copy_from_user(dst, (const void __user *)unsafe_src, size); > > I don't know if it matters what we return here so long as it's non-zero. > This is probably a fast path so maybe we're returning positives > intentionally? > > 3558 > 3559 ret = access_process_vm(tsk, (unsigned long)unsafe_src, dst, size, 0); > 3560 if (ret != size) > 3561 return -EFAULT; > 3562 return 0; > 3563 } > > regards, > dan carpenter > Hi, thanks for the report, I think the warning is right, let me send the fix a bit later today.